A geography of moral hazard: sources and sinks of motor-vehicle commuting externalities.

Motor-vehicles are responsible for harms to health that are not directly experienced by individual drivers - such as air pollution and risk of injury to pedestrians. In addition to their direct effects on health, these harms also represent a moral hazard since drivers are not required to consider their effects as part of their decision to drive. We describe an approach for estimating sources of motor-vehicle commuter externalities as a means of understanding the geography of moral hazard, and in particular, the spatial displacement of negative health externalities associated with motor-vehicle commuting. This approach models motor-vehicle commuter traffic flow by trip origin for small geographic areas within the City of Toronto, Ontario. We find that most health-related externalities associated with motor-vehicle commuters are not locally generated, with a large share coming from outside Toronto. Low income is associated with externalities originating outside the municipal boundary, but not with locally sourced externalities. We discuss the impact of geographical moral hazard on the agency of citizens as well as policy options aimed at addressing motor-vehicle externalities.

Altering school attendance times to prevent child pedestrian injuries.

OBJECTIVES: The purpose of this research was to determine whether modifying school start time schedules can be used to reduce children's exposure to traffic on their morning walks to school. METHODS: We use models of pedestrian and motor vehicle commuting to estimate the frequency of encounters between child pedestrians and motor vehicles at intersections throughout the City of Hamilton, Ontario, Canada. We use a simple heuristic to identify the school-specific start times that would most reduce the local frequency of encounters between motor vehicles and pedestrians. RESULTS: Our analysis suggests that it may be possible to achieve an almost 15 percent reduction in the total number of encounters between child pedestrians and motor vehicles during the morning commute by staggering school start times such that the periods of high pedestrian activity are temporally staggered from periods of high motor vehicle activity. Our analysis suggests that small changes in school start times could be sufficient to see noteworthy reductions in pedestrian exposure to traffic. CONCLUSIONS: Changing school times may be an effective, inexpensive, and practical tool for reducing child pedestrian injuries in urban environments. Enhanced transportation models and community-based interventions are natural next steps for exploring the use of school-specific scheduling to reduce the risk of child pedestrian injury. Further research is required to validate our models before this analysis should be used by policy makers.